Steering systems in automobiles originally were largely mechanical in nature. Oftentimes, the steering wheel had some type of a pinion or other gear that actuated a rack connected to the front wheels of the automobile. As the wheel was turned, the rack moved the wheels left-or-right depending upon the direction of turn.
Steering systems have increasingly relied upon intervening electronic systems and mechano-electric (hydraulic) systems for safety, control and other purposes. Conventional systems employ position detectors connected to the steering components, such as the shaft or rack of the steering system. These position detectors may, for example, be based on optical or potentiometer position detection methods. Automotive and other manufacturers, however, find that the cost and lack of robustness of these position detectors are problematic.
In addition, some conventional systems may employ a Hall effect torque sensor on steering wheel components, such as a shaft connected to the steering wheel. For example, U.S. Pat. No. 5,238,076 (“the '076 patent”) describes an electric power steering system. The electric power steering system includes a steering wheel torque sensor that delivers an all or nothing signal. However, delivering an all or nothing signal does not provide linear torque values measured across a torsional member. Other systems also use traditional Hall effect sensors that are relatively large and expensive to manufacture. Hall effect sensors also have a delay when providing feedback. The delay can be critical in time-sensitive areas such as controlling the angle of a steering wheel and other vehicle systems.
It would be advantageous to have a robust, cost-effective sensor system for determining relative positions of two or more objects. In particular, it would be advantageous to have a sensor system capable of robustly and accurately determining the position of steering components with a relatively low cost.